Getting to dos without a drive

How can I get into dos without an A drive? I need to get into dos to flash the bios on one of my PC's because basically it's pretty trashed and I'm thinking this might be the last possible way to fix it. Then I try to make a floppy disk but the drive is busted. I was thinking along the way of a bootable CD to act like a floppy but I'm not sure what to put on it, if anyone could point me in the right direction it would be a big help.

Make a boot CD and set your optical drive as the first boot device (and HDD-0 as the second)

http://www.nu2.nu/bootcd/
http://www.ultimatebootcd.com/

Mine includes Partition Magic 8 and 4 different boot-to-DOS modes.

ok looking at the ultimate boot CD, I didn't totally understand the first website, what exactly should I put on the CD from the ultimate boot CD site to accomplish what i want (booting to dos)

Actually, I made a disk image a while ago so you don't have to. Simply unzip the image from this file and use Nero or Easy CD Creator to burn a disc from image using it.

http://members.aol.com/captainslg/cdboot.zip

It will boot to a prompt menu which gives you the option of a command prompt with CD-ROM support. I didn't put any tools on it because I can run those directly off of other CDs. The disc image is really just for empty booting a machine without a hard drive.